TULSA, Okla.  Police believe separate shootings in Tulsa, Okla., in which three people were killed and two others were critically wounded, are linked.

Homicide detective Sgt. Dave Walker says investigators don't have the results of forensic testing yet. But he says police think the same attacker or attackers are behind the early Friday morning attacks because they happened in quick succession within three miles of one another, and because all five victims were out walking when they were shot.

Police don't believe the victims knew one another and are trying to determine the circumstances behind the killings.

All five victims are black, and The Tulsa World reports that black community leaders met Friday evening in an effort to calm unrest and promote safety.